There is a need for a solar photovoltaic installation which can provide low cost power during normal times and emergency power during power outages on the grid which is not tied directly to the grid. Grid-tied solar inverters are required to shut down during grid outages, per IEEE Standard 1547, to prevent solar power from feeding back onto a downed line and endangering utility personnel trying to fix the problem. Thus the grid-tied solar installation is compelled to shut down just when its power is most needed. The only available alternatives are multi port inverter systems, such as those supplied by Princeton Power Systems, Ideal Power or Pika Energy or battery-supported back up systems such as the Sunny Island system of SMA, and Magnum Energy Systems, both of which are quite expensive.
There is another problem with conventional grid-tied solar systems in that the utilities are beginning to disfavor them as a threat to their business and a destabilizing element in the grid. Grid-tied solar systems can inject power at any time, and their output is uncontrollable and highly variable. As a result consumers who want the benefits of solar energy are not able to obtain permits to net meter from their local Electric Distribution Company (EDC), and without net metering, solar systems sized to deliver more power than the household can use are uneconomic.
There is yet another problem in that owners of battery storage systems who can ride through outages with their solar energy intact and who could provide ancillary frequency and voltage regulation services to the grid by taking and returning power from the battery are forbidden to do so by rules specifying that only “renewable” energy may be net metered, and that energy stored in the battery may not be “injected” into the grid.
There is the further problem that battery storage in the amount necessary to provide useable emergency power in an outage lasting more than an hour or so is very expensive. A typical household consumes electric energy at the average rate of 1 kW and a 24 kWh battery to last one day will cost approximately $10,000.
It is an objective of this invention to provide an inexpensive, non-grid-tied solar system with storage that can provide low-cost solar power to critical household loads during normal times and emergency power throughout power outages of whatever duration. The system relies on an electric vehicle main propulsion battery to supply massive storage capacity without the necessity for investing in a major fixed storage battery. The system can be installed without a net meter connection to the local EDC or any other special permits, as long as local electrical codes are complied with. It can even provide regulation service without “Injection”.